Photovoltaic devices, i.e., solar cells, are capable of converting solar radiation into usable electrical energy. The energy conversion occurs as the result of what is known as the photovoltaic effect. Solar radiation impinging on a solar cell and absorbed by an active region of semiconductor material generates electricity.
In recent years, technologies relating to thin-film solar cells have been advanced to realize inexpensive and lightweight solar cells and, therefore, thinner solar cells manufactured with less material have been demanded. This is especially true in the space industry with the solar cells powering satellites and other space vehicles.
The current state of the art in solar cell design is to deposit a photoactive material onto a dense substrate. Typically, the substrate was constructed of glass or a low expansion glass ceramic with densities of approximately 2.2 gms/cc (2200 mg/cc) or higher. Accordingly, the weight of an array or battery of such prior art solar cells is a determining factor in the size of the battery system to be launched into space due to payload weight constraints. Heavy solar cells increase the cost of positioning the satellite into orbit and the operating costs by reducing the payload of the satellite and increasing the launch weight. A lighter weight cell substrate would provide savings in size and weight thereby translating into an increased size for satellite photovoltaic energy systems, which implies higher reliability and accessibility of the satellite throughout its life cycle.
Accordingly, there exists a need for a thin-film solar cell fabricated on a flexible metallic substrate which is inexpensive to manufacture. Additionally, a need exists for a thin-film solar cell fabricated on a flexible metallic substrate which is lightweight and reliable for use in space vehicles and other applications. Furthermore, there exists a need for a thin-film solar cell fabricated on a flexible metallic substrate wherein the flexible metallic substrate is an aluminum substrate or a stainless steel substrate with appropriate means between the aluminum substrate and the semiconductor absorber for inhibiting reaction between the aluminum substrate and the semiconductor absorber.